66 METEOROLOGICAL 



Weissenborn, in 1818, where the light travelled 

 over a distance of half a mile in less than a second. 

 (Mag. of Nat. Hist. N.S. i. 553.) 



From these facts, it appears probable to modern 

 philosophers, that there are two kinds of ignes 

 fatui, the one referable to spontaneously inflam- 

 mable gas, the other to luminous insects. 



If phosphuretted hydrogen, or any other spon- 

 taneously combustible gas or liquid, caught fire 

 upon a marsh where carburetted hydrogen (marsh 

 gas) is constantly evolved, the latter would in- 

 flame also.* 



In the valley of Gorbitz, Mr. Blesson discovered 

 a light emanating from marshy ground. Remain- 

 ing for some days near the place, in order to study 

 the phenomenon as closely as possible, he found 

 it was owing to an ignited gas, the faint flame of 

 which was invisible during the day, but became 

 gradually visible in the evening. The gas appears 

 to have been carburetted hydrogen, or marsh gas. 

 As he approached it, the flame receded, but he 

 eventually succeeded in lighting a piece of paper 

 by it. 



According to some authors, Will-o' -the- Wisp 

 may be seen at all seasons of the year; but a great 



* At Wigmore, in Herefordshire, and other places in England, 

 carburetted hydrogen used to be so abundant in the ground that 

 it was employed for lighting and cooking in the houses, as we 

 learn from travellers is a common practice in China. 



